Connector for domed cutting tool

ABSTRACT

The surgical reamer has a hollow dome with apertures spaced apart arranged in arcs extending from an apex of the dome to the base portion of the dome, and removable teeth positioned in the apertures. Each cutting tooth has a flange that is aligned flush with the external surface of the dome, and a raised cutting edge extending above the flange and the external surface of the dome, and an interior passageway communicating between the outside and inside of the dome. In one embodiment, a base plate is removably secured on the base portion of the dome to provide closure of the central cavity of the dome.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of Ser. No. 10/359,605 entitledCONNECTOR FOR DOMED CUTTING TOOL, which is a continuation of Ser. No.09/671,234, filed on Sep. 19, 2000 and based on PCT/US99/05951 havingInt. Filing Date of Mar. 18, 1999, which in turn has the benefit ofpriority based on Ser. No. 09/040,861 filed Mar. 18, 1998 (now U.S. Pat.No. 5,976,144).

TECHNICAL FIELD

This invention relates generally to surgical devices, and moreparticularly concerns a rotatable surgical cutting tool for shaping ajoint socket in preparation for receiving a joint prosthetic device.

BACKGROUND OF THE INVENTION

It is now common practice in the treatment of severe cases of arthriticand other forms of degenerative joint diseases, especially the hip, toshape the hip joint socket by removing diseased and eroded bone andcartilage to conform with the shape of a prosthetic device to beimplanted. Prior to installing a hip joint prosthesis, for example,articular cartilage and bone is commonly removed from the socket toreshape the acetabulum to accurately match the dimensions of theprosthetic device to be implanted. In the past, the tissue and debrisremoved from the hip socket was discarded; however, more recently, ithas become important to capture the debris for preservation and uselater in the procedure.

It is generally desirable for milling devices and reamers used inpreparing a joint socket for a prosthesis to have cutting edges that cancut through a wide variety of tissue, such as joint cartilage and bonetissue, ranging in density from the soft or porous tissue to the denserbone. The surgical tools with hollow cutting heads are more widely usedthan other more open designs, because hollow head devices allow tissueand other debris to be captured within the cutting head.

Two distinct types of hollow dome cutting tools are currently availablethat capture the debris. One type employs a slotted dome with adjacentblades that are shaped to generate a socket, when rotated, conforming tothe shape and dimensions of the prosthesis to be implanted. The debriscut by the blades falls through slots in the dome.

In another type of surgical milling tool, commonly called a “grater”reamer, the milling cutters are formed on the body by upsetting the bodyaround openings in the body, and sharpening selected edges of the upsetportions of the body. The surgical milling tool has a body with ahemispherically-shaped outer surface, an internal cavity, and millingcutters formed out of the perforations in the body at spaced-apartlocations on the outer surface. The tool can be rotated in a jointsocket to mill the tissues of the joint socket, such as for preparationof the joint socket for a prosthesis. The perforations in the bodycommunicate with the internal cavity which receives the debris. Themilling cutters of the milling tool are formed as cup-shaped projectionsextending above the perforations that face in a direction of rotation,and are arranged in a series of arcs extending circumferentially aroundthe body. The outer wall of the milling tool forming the cup-shapedcutting edge projections is relatively thin, resulting in reducedcutting accuracy. The milling tool and cutting edge projections areformed of sheet steel, which can become dull relatively rapidly duringuse. Typically, if the cutting surfaces are formed integrally with theshell, such as with raised cutting edges formed directly in the shell,the manufacturing of the devices becomes very costly. In addition, oncethe projections forming the cutting edges of the milling tool are dull,the entire milling tool is typically discarded.

An example of a grater type of reamer is shown in U.S. Pat. No.5,658,290 to Lechot, which further provides radial rods on the undersideof the reamer cap that join up at the center of the cap and areintegral. A reamer spindle has a shank with a head equipped with abayonet having a locking mechanism for securing the reamer. The centerof the bayonet is recessed to receive the radial rods and serve as acavity for debris.

It would be desirable to provide a reaming tool fabricated from heattreated machined metal components to provide greater cutting accuracy,and at lower manufacturing costs than conventional surgical cutters. Inthis regard it would be desirable to form the cutters of a hardenedcutting material to provide superior cutting edges. In addition, itwould be desirable to provide a reaming tool with replaceable cuttingedges, so that once the cutting edges become dull, they can be removed,resharpened, and replaced, for improved economy of use and maintenance.The present invention meets these needs.

It would be further desirable to provide a reaming tool that not onlycaptures debris passing through the teeth, but one that also allowseasier removal and use of the debris collected within the tool, versuscurrently available tools. The present invention is also an improvedmeans for meeting this need.

SUMMARY OF THE INVENTION

Briefly, and in general terms, the present invention provides for animproved reaming tool that is fabricated from machined metal componentsto provide greater cutting accuracy, and at lower manufacturing coststhan conventional cutters. The reaming tool has a multiplicity ofcutters that can be formed of heat treated tool steel, to providesuperior cutting edges. In addition, once the individual cutters becomedull, they can readily be removed, replaced, and can even be resharpenedand used again, for improved economy of use and maintenance.

The present invention accordingly provides for a rotary surgical reamerfor removing bone and tissue from a joint to facilitate the installationof a prosthetic device. The rotary surgical reamer comprises a hollowreamer body, the hollow reamer body having a base portion, a wall with asurface defining a central cavity and a plurality of spaced apartapertures through the wall at a plurality of spaced apart locations onthe wall defining cutting sites. Means are provided for connecting thehollow reamer body to a source of rotary power, and a plurality of teethare removably disposed in the apertures. Each of the teeth have a toothbody having a base portion and a raised cutting edge, and the tooth bodyincludes means for holding the tooth in a fixed position at one of thecutting sites. The tooth body also has a surface defining a passagewaycommunicating between the external surface of the wall and the centralcavity for passage of removed bone and tissue through the wall into thecentral cavity. In a currently preferred embodiment, the tooth bodyincludes a flange for spacing the cutting edge a desired distance beyondthe external surface of the wall of the reamer body. In one presentlypreferred embodiment, the teeth have a generally tubular shape.

The hollow reamer body preferably has a shape with a central axis ofrotation about which perpendicular cross-sectional cutting patterns aregenerated during rotation of the hollow reamer body, allowing the hollowreamer body to be rotated without wobbling. In one presently preferredembodiment, the external surface of the hollow reamer body has athree-dimensional contour that is generally hemispherical, although thehollow reamer body may also have a three-dimensional contour selectedfrom the group consisting of generally spherical, oblate spheroid,generally cylindrical, generally polygonal, or combinations thereof.Means for connecting the hollow reamer body to a source of rotary poweris carried on the base portion of the hollow reamer body.

In one presently preferred embodiment, the external surface of thehollow reamer body has a three-dimensional contour having an apex, andthe plurality of cutting sites are spaced apart in an arcuate arrayextending from a site adjacent the apex toward the base portion of thehollow reamer body, forming a helical pattern. In another presentlypreferred embodiment, the cutting sites are arranged in a plurality ofarcs extending from a site adjacent to an apex of the hollow reamer bodyto the base portion.

In another preferred aspect of the invention, the rotary surgical reamerincludes closure means adapted to be secured to the base portion of thehollow reamer body. In a presently preferred embodiment, the closuremeans comprises a base plate removably disposed on the base portion ofthe hollow reamer body and means for securing the base plate to the baseportion of the hollow reamer body for closure of the central cavity ofthe hollow reamer body. The internal surface of the central cavitypreferably defines at least one inner annular groove, and the means forsecuring the base plate to the base portion of the hollow reamer bodycomprises a retaining spring having first and second ends and having arelaxed bent configuration and a compressed configuration in which theends of the retaining spring can be extended into the inner annulargroove of the base portion of the hollow reamer body.

A drive shaft is also provided for transmitting torque for rotation ofthe hollow reamer body, the retaining spring having a surface defining acentral aperture for receiving the drive shaft, and the base platehaving a surface defining a central aperture for receiving the driveshaft for transmitting torque for rotation of the hollow reamer body.The drive shaft has a terminal end that is press fit into the centralaperture in the base plate, and the terminal end of the drive shaft hasa transverse aperture in the shaft, and a retaining pin adapted to bereceived in the transverse aperture that when received in the transverseaperture extends above the surface of the shaft, for securing the driveshaft to the base plate.

In one currently preferred embodiment, the means for securing the baseplate to the base portion of the hollow reamer body includes a retainingspring having a relaxed bent configuration and a compressed,substantially flat configuration in which the terminal ends of theretaining spring can be extended into the inner annular groove of thebase portion of the hollow reamer body. The retaining spring alsopreferably has a central aperture with a notch to allow the drive shaftto pass through the retaining spring.

A tubular collar is provided for securing the retaining spring in thecompressed configuration. The tubular collar is provided with a keywayfor receiving a retaining pin inserted in the shaft, such that thetubular collar can be placed over the shaft and pressed against theretaining spring and rotated to lock the pin in the collar in a positionpressing against the retaining spring, so that the retaining spring islocked in the flattened configuration.

In an alternate preferred embodiment, the hollow reamer body comprises ahollow can having a base portion, a wall with a top surface and aninternal surface defining a central cavity and a plurality of spacedapart cutting sites on the wall. The hollow can has a central axis ofrotation about which perpendicular cross-section cutting patterns aregenerated upon rotation of the hollow can, allowing the hollow can to berotated without wobbling. The base portion of the hollow can alsopreferably includes means for connecting the hollow can to a source ofrotary power. In this embodiment, the plurality of cutting sitescomprises a site located adjacent to the axis of the can, with aplurality of sites arrayed in a plurality of arcs extending on the topsurface of the can from the axis of the can to the edge of the topsurface.

In another general aspect of the invention, a rotary surgical reamercomprises a hollow reamer body having a wall with an external surfaceand a periphery, the wall defining a central cavity and a plurality ofspaced apart apertures through the wall at a plurality of spaced apartlocations on the wall defining cutting sites. The cutting sites definepassageways communicating between the external surface of the wall andthe central cavity for passage of removed bone and tissue through thewall into the central cavity. A single mounting bar extendsdiametrically across and is affixed to a back side of the periphery, themounting bar having means for attaching a powered rotary driver thereto.

In yet another general aspect of the invention, a rotary surgical reamercomprises a hollow reamer body having a wall with an external surfaceand a periphery, the wall defining a central cavity and a plurality ofspaced apart apertures through the wall at a plurality of spaced apartlocations on the wall defining cutting sites. The cutting sites definepassageways communicating between the external surface of the wall andthe central cavity for passage of removed bone and tissue through thewall into the central cavity. A pair of parallel mounting bars extendchordally across and are affixed to a back side of the periphery, themounting bars having means for attaching a powered rotary driverthereto.

In still another general aspect of the invention, a rotary surgicalreamer comprises a hollow reamer body having a wall with an externalsurface and a periphery, the wall defining a central cavity and aplurality of spaced apart apertures through the wall at a plurality ofspaced apart locations on the wall defining cutting sites. The cuttingsites define passageways communicating between the external surface ofthe wall and the central cavity for passage of removed bone and tissuethrough the wall into the central cavity. Removable teeth are located atsubstantially all of the cutting sites. An array of three radialmounting bars extend inwardly from and are affixed to a back side of theperiphery, the mounting bars having means for attaching a powered rotarydriver thereto.

These and other aspects and advantages of the invention will becomeapparent from the following detailed description and the accompanyingdrawings, which illustrate by way of example the features of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an hollow dome reamer with removable,replaceable cutters according to the present invention;

FIG. 2 is a top plan view of the hollow dome reamer of FIG. 1;

FIG. 3 is a side elevational view of the hollow dome reamer of FIG. 1;

FIG. 4 is a cross-sectional view of the hollow dome reamer taken alongline 4—4 of FIG. 2;

FIG. 5 is a bottom plan view of the hollow dome reamer of FIG. 1;

FIG. 6 is a side elevational view of a portion of the hollow dome reamertaken along line 6—6 of FIG. 4;

FIG. 7 is a schematic diagram of a pattern of placement of the cuttersof the hollow dome reamer;

FIG. 8 is a schematic diagram of an alternate pattern of placement ofthe cutters of the hollow dome reamer;

FIG. 9 is a side elevational view of a cutter of the hollow dome reamerof FIG. 1 according to the invention;

FIG. 10 is a bottom plan view of the cutter of FIG. 9;

FIG. 11 is a perspective view of the cutter of FIG. 9;

FIG. 12 is a bottom plan view of the base plate and drive shaft of thehollow dome reamer of FIG. 1 according to the invention;

FIG. 13 is a side elevational view of the base plate of FIG. 12, shownwithout the drive shaft, for the sake of simplicity;

FIG. 14 is a side elevational view of a portion of the base plate takenalong line 14—14 of FIG. 12, showing a key flange corresponding to thenotches in the dome;

FIG. 15 is another side elevational view of the base plate and driveshaft of the hollow dome reamer of FIG. 1 showing the placement of aretaining pin according to the invention;

FIG. 16 is a side elevational view of a retaining collar for compressingthe retaining spring to engage the inner annular groove of the dome,according to the invention;

FIG. 17 is another side elevational view of the base plate and driveshaft of the hollow dome reamer of FIG. 1 showing the placement of aretaining spring over the drive shaft and retaining pin according to theinvention;

FIG. 18 is a plan view of the retaining spring of FIG. 17 according tothe invention;

FIG. 19, is a plan view of a ring lock spring adapted to be received onthe annular groove of the drive shaft;

FIG. 20 is a partial view of a hollow drive rod adapted to fit over thedrive shaft and ring lock spring;

FIG. 21 is a sectional view of an alternate embodiment of a hollowreamer body of the hollow dome reamer of the invention having a shapefor use as a glenoid reamer;

FIG. 22 is a sectional view of another alternate embodiment of a hollowreamer body of the hollow dome reamer of the invention having aninverted curved shape for use as a femur or glenoid reamer;

FIG. 23 is a sectional view of another alternate embodiment of a hollowreamer body of the hollow dome reamer of the invention having a tieredshape with flattened shoulders for use as a patella recessing tool;

FIG. 24 is a top plan view of the hollow reamer body of FIG. 23 showingthe pattern of the cutting teeth;

FIG. 25 is an external perspective view of the underside of a reamerhaving a single peripherally emanating mounting bar, according to theinvention;

FIG. 26 is a bottom view of the reamer of FIG. 25;

FIG. 27 is a bottom view of the underside of a reamer having a pair ofperipherally emanating parallel mounting bars, according to theinvention;

FIG. 28 is a bottom view of the underside of a reamer having atriangular array of peripherally emanating radial mounting bars,according to the invention;

FIG. 29 is a bottom view of the underside of a reamer having analternative triangular array of peripherally emanating mounting bars ofthe invention;

FIG. 30 is a side view of a preferred driver of the invention, shownwith the reamer of FIGS. 25-26 prior to assembly;

FIG. 31 is a perspective view of FIG. 30; and

FIG. 32 is an enlarged perspective view of the driver and reamer dome ofFIG. 30, shown assembled with one another.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

During surgery for preparation of a joint for installation of a jointprosthesis, it has become important to capture and preserve the tissueand debris removed from a joint for later use. However, conventionalsurgical tools with hollow cutting heads that are typically used forthis type of surgery commonly have cup-shaped cutting edge projectionsthat are relatively thin, become dull relatively rapidly during use, andare not readily sharpened or replaced, so that once the cutting edges ofthe surgical tool become dull, the surgical tool is useless.

As is illustrated in the drawings, the invention is accordingly embodiedin a hollow dome reamer that provides greater cutting accuracy, withremovable teeth having superior cutting edges. The removable teeth canreadily be replaced, and resharpened for repeated usage. Referring toFIGS. 1 through 11, the hollow dome reamer 20 is preferably a rotarysurgical reamer having a plurality of inserted modular teeth 22 orcutters that are removably disposed in a hollow reamer body or dome 24having a plurality of apertures 26 formed therein spaced apart atvarious locations around the dome. In one presently preferredembodiment, the dome has a hemispherical shape, although other threedimensional geometrical shapes may also be desirable and suitable fordifferent applications, and in general the dome may be shaped to begenerally spherical, an oblate spheroid, generally cylindrical,generally polygonal, and combinations thereof. The dome is alsoadvantageously shaped to have a central axis of rotation about whichperpendicular cross-sectional cutting patterns are generated duringrotation of the hollow reamer body, allowing the hollow reamer body tobe rotated without wobbling. In a presently preferred embodiment, theteeth are tubular, and the apertures are correspondingly cylindrical toaccept the tubular teeth, but other geometrical shapes of the teeth andthe apertures may also be suitable. The apertures of the dome and thetubular teeth are currently preferably dimensioned so that the tubularteeth can be press fit into the apertures in the dome; althoughthreading the tubular teeth and the apertures to have correspondingthreads to allow the tubular teeth to be threadedly secured in the dome,and other similar ways of securing the tubular teeth in the cylindricalapertures of the dome may also be suitable.

As can best be seen in FIGS. 2, 3, 5, 7 and 8, the apertures arepreferably arranged in a plurality of arcs 28 extending from an apex 30of the dome to the base portion 32 of the dome. In one presentlypreferred embodiment illustrated in FIGS. 1 to 5 and 7, a tubular cutteror tooth is provided in an apex aperture located off-center at the apexof the dome, with tubular teeth being provided in a series of threeequally spaced arcs of spaced apart apertures, each of the arcscommencing at the center of the apex aperture and extending to theperiphery of the base portion, with the apertures in the arcs beingregularly spaced apart at pre-determined distances along the arcs. Inthis embodiment, there are currently preferably three equally spacedarcs, with three regularly spaced apertures in each arc, but greaternumbers of arcs may also be suitable.

In an alternative preferred embodiment illustrated in FIG. 8, a tubulartooth is provided in an apex aperture located adjacent to the apex ofthe dome, with tubular teeth being provided in an arcuate, generallyhelical path of spaced apart apertures, the arc commencing generally atthe apex of the dome and extending to the periphery of the base portion.The apertures in the helical arc are preferably spaced apart atpre-determined distances along the arcs such that all of the aperturesfall on a spiral line extending from the apex aperture of the dome tothe periphery of the base portion.

Referring to FIGS. 4 and 5, the dome has an inner central cavity 34 orchamber, a hemispherical external surface 36, and an outer wall 38having a thickness that is sufficient to provide adequate support for aplurality of the tubular teeth disposed in the apertures of the dome.Each tubular tooth preferably also has an interior passageway 39, sothat when the teeth are inserted in the apertures of the dome, thehollow tubular teeth provide communication between the external andinternal areas of the dome through the wall. As explained above, whilethe teeth are currently preferably tubular, and the apertures arecylindrical, other cross-sectional shapes of the teeth and apertures mayalso be suitable as long as an interior passageway is provided in theteeth, and the teeth can be removably disposed in the apertures of thedome.

The base portion of the dome preferably has at least one inner annulargroove 40 that can be seen in FIG. 4, for receiving the terminal ends 42of a retaining spring 44 of the base plate, and a plurality of notches46 adapted to receive corresponding key flanges 48 of the base plate,described below. In one presently preferred embodiment, the base portionof the dome has two diametrically opposed notches adapted to receivecorresponding key flanges of the base plate. The dome is currentlypreferably formed from metal, such as steel, such as stainless steel ortool steel for example, titanium alloy, aluminum, aluminum alloy,nitinol, and molybdenum, although the dome can be made of other suitablematerials, such as ceramic or plastic, for example.

As can best be seen in FIGS. 9 and 11, the tubular teeth each have araised cutting edge 50, a tubular base portion 51, and a flange 52 orshoulder that is aligned with the hemispherical external surface of thedome to position the cutting edges of the teeth at a specific desireddistance above or beyond the hemispherical external surface of the dome.The teeth are currently preferably fabricated of heat treated toolsteel, although the teeth can also be formed from other suitablematerials, such as stainless steel, ceramic, plastic, titanium alloy,aluminum alloy, nitinol, and molybdenum. Each cylindrical, tubular toothinsert is preferably formed by cutting a tube formed of tool steel intosegments, and grinding down a portion of one end of a segment to formthe flange or shoulder, and leaving the raised portion of the end of thesegment as the cutting edge. The cylindrical, tubular tooth insert isthen press fit in an aperture of the dome, oriented so that the flangeis flush with the external surface of the dome and facing in a directionof rotation 54 of the dome, so that when the dome is rotated in thespecified direction, the raised circular cutting edge section willperform the cutting of bone and other tissue, which will then beextruded through the central hole or passageway 39 in the tooth and intothe central cavity of the dome.

With reference to FIGS. 12 to 14, the hollow dome reamer also includes acircular base plate 56 with a plurality of key flanges 48 adapted to bereceived in the corresponding notches 46 of the base portion of thedome. The base plate is removably disposed on the base portion of thedome, and achieves closure of the central cavity of the dome. In acurrently preferred embodiment, the circular base plate has a pair ofdiametrically opposed key flanges, and means 58 for securing the baseplate to the base portion of the dome.

In a currently preferred embodiment, the means for securing the baseplate to the base portion of the dome comprises a leaf spring retainingspring 44 shown in FIGS. 17 and 18 that has a compressed, considerablyflattened configuration in which the terminal ends of the retainingspring can be extended into the inner annular groove 40 of the baseportion of the dome, and a relaxed, slightly bent configurationillustrated in FIG. 17 in which the terminal ends of the retainingspring do not extend into the inner annular groove of the base portionof the dome. The retaining spring preferably has a central aperture 66to allow passage of a drive shaft, shown in FIGS. 15 and 17, through theretaining spring, and the circular base plate also has a centralaperture 68 for receiving the drive shaft. The drive shaft 70 isprovided for transmitting torque for rotation of the dome. The driveshaft has a terminal end 72 that is press fit into the aperture 68 inthe base plate. The terminal end 72 of the shaft also has an aperture 74for receiving a retaining pin 76 that, when received in the aperture ofthe terminal end of the drive shaft, extends above the surface of thedrive shaft, for securing the drive shaft to the base plate. Theretaining spring central aperture also includes a notch 77 to allow theretaining spring to slide over the retaining pin 76 of the drive shaft.

Referring to FIGS. 16 and 17, a tubular collar 78 having a keyway 80 forreceiving the pin of the shaft is also provided that fits over the driveshaft. The collar can be pressed against the retaining spring to flattenit, and then rotated to lock the pin in the keyway of the collar, sothat the retaining is locked in a flattened configuration.

With reference to FIGS. 15 and 19, the proximal end 82 of the driveshaft also preferably has an annular groove 84 for receiving an annularspring lock 86 shown in FIG. 19. The spring lock comprises a main loop88 that is received in the annular groove of the drive shaft, an arm 90extending generally perpendicular to the curve of the loop, and a balltip 92 at the distal end of the arm. Referring to FIG. 20, the arm andball tip of the spring lock are adapted to be received in a slot 94 of aslotted collar 96 of a hollow drive rod 98, adapted to be connected to asource of rotary drive power, such as an electric drill motor.

FIG. 21 illustrates a first variant of the shape of the hollow reamerbody illustrated in FIGS. 1-8, adapted for use as a glenoid reamer. Inthis variant, the shape of the external cutting surface of the hollowreamer body can be generally convex. but not necessarily hemispherical,and is similar in many respects to the embodiment illustrated in FIGS.1-8, so that elements of the first variant that are similar to those ofthe first embodiment described above are described with similarreference numbers. The convex hollow dome glenoid reamer 120 preferablyhas a plurality of inserted modular teeth 122 that are removablydisposed in the hollow reamer body or dome 124 having a plurality ofapertures 126 formed therein spaced apart at various locations aroundthe dome. The dome of the glenoid reamer is shaped to have a centralaxis of rotation about which perpendicular cross-sectional cuttingpatterns are generated during rotation of the hollow reamer body,allowing the hollow reamer body to be rotated without wobbling.

As was illustrated in FIGS. 1-5 and 7-8 in connection with the firstembodiment, in the glenoid variant of the hollow dome reamer, theapertures are preferably arranged in a plurality of arcs extending froman apex of the dome to the base of the dome. Alternatively, a tubulartooth can be provided in an apex aperture located adjacent to the apexof the dome, with tubular teeth being provided in an arcuate, generallyhelical path of spaced apart apertures, the arc commencing generally atthe apex of the dome and extending to the periphery of the base portion.

The hollow reamer body or dome has an inner central cavity 134 orchamber, an external surface 136, and an outer wall 138 having athickness that is sufficient to provide adequate support for a pluralityof the tubular teeth disposed in the apertures of the dome. The cuttingteeth are as described hereinabove. As explained above, while the teethare currently preferably tubular, and the apertures are cylindrical,other cross-sectional shapes of the teeth and apertures may also besuitable as long as an interior passageway is provided in the teeth, andthe teeth can be removably disposed in the apertures of the dome. Thebase portion 132 of the dome preferably has an integral base plate 140having an aperture for receiving a drive shaft for supplying rotarypower to the reamer.

In another presently preferred variant of the hollow reamer bodyillustrated in FIG. 22, the shape of the hollow reamer body is adaptedfor use as a femur or glenoid reamer. In this second variant, the shapeof the external cutting surface of the hollow reamer body can begenerally concave, but not necessarily hemispherical, and is similar inmany respects to the embodiment illustrated in FIG. 21, so that elementsof this second variant that are similar to those described above aredescribed with similar reference numbers. The hollow dome glenoid reamer220 preferably has a plurality of inserted teeth 222 that are removablydisposed in the hollow reamer body or dome 224 having a plurality ofapertures 226 formed therein spaced apart at various locations aroundthe dome. The dome of the concave femur or glenoid reamer is shaped tohave a central axis of rotation about which perpendicularcross-sectional cutting patterns are generated during rotation of thehollow reamer body, allowing the hollow reamer body to be rotatedwithout wobbling.

As was illustrated in FIGS. 1-5 and 7-8 in connection with the firstembodiment, in the glenoid variant of the hollow dome reamer, theapertures are preferably arranged in a plurality of arcs extending froman apex of the dome to the base of the dome. Alternatively, a tubulartooth can be provided in an apex aperture located adjacent to the apexof the dome, with tubular teeth being provided in an arcuate, generallyhelical path of spaced apart apertures, the arc commencing generally atthe apex of the dome and extending to the periphery of the base portion.

The hollow reamer body or dome has an inner central cavity 234 orchamber, an external surface 236, and an outer wall 238 having athickness that is sufficient to provide adequate support for a pluralityof the tubular teeth disposed in the apertures of the dome. The cuttingteeth are as described hereinabove. As explained above, while the teethare currently preferably tubular, and the apertures are cylindrical,other cross-sectional shapes of the teeth and apertures may also besuitable as long as an interior passageway is provided in the teeth, andthe teeth can be removably disposed in the apertures of the dome. Thebase portion 232 of the dome preferably has an integral base plate 240having an aperture for receiving a drive shaft for supplying rotarypower to the reamer.

In another presently preferred variant of the hollow reamer bodyillustrated in FIGS. 23 and 24, the shape of the hollow reamer body isadapted for use as a patella recessing tool. In this third variant, theshape of the external cutting surface of the hollow reamer body can begenerally tiered to have two or three tiers for example. Referring tothe specific embodiment shown in FIGS. 23 and 24, the patella recessingreamer provides a generally flat raised first inner tier 316, and agenerally flat lower second tier 318. This embodiment is similar in manyrespects to the embodiments illustrated in FIGS. 21 and 22, so thatelements of this third variant that are similar to those described aboveare described with similar reference numbers. The hollow dome patellarecessing reamer 320 preferably has a plurality of inserted teeth 322that are removably disposed in the hollow reamer body or dome 324 havinga plurality of apertures 326 formed therein spaced apart at variouslocations around the dome. The dome of the tiered patella recessingreamer is shaped to have a central axis of rotation about whichperpendicular cross-sectional cutting patterns are generated duringrotation of the hollow reamer body, allowing the hollow reamer body tobe rotated without wobbling.

As is shown in FIG. 24, in the patella recessing variant of the hollowdome reamer, the apertures are preferably arranged in a plurality ofarcs extending from an apex of the dome to the base of the dome.Alternatively, a tubular tooth can be provided in an apex aperturelocated adjacent to the apex of the dome, with tubular teeth beingprovided in an arcuate, generally helical path of spaced apartapertures, the arc commencing generally at the apex of the dome andextending to the periphery of the base portion.

The hollow reamer body or dome has an inner central cavity 334 orchamber, an external surface 336, and an outer wall 338 having athickness that is sufficient to provide adequate support for a pluralityof the tubular teeth disposed in the apertures of the dome.

The cutting teeth are as described hereinabove. As explained above,while the teeth are currently preferably tubular, and the apertures arecylindrical, other cross-sectional shapes of the teeth and apertures mayalso be suitable as long as an interior passageway is provided in theteeth, and the teeth can be removably disposed in the apertures of thedome. The base portion 332 of the dome preferably has an integral baseplate 340 having an aperture for receiving a drive shaft for supplyingrotary power to the reamer.

It has thus been demonstrated that the present invention provides for areaming tool that provides greater cutting accuracy, with tubular teethsuperior cutting edges that can readily be removed, replaced, andresharpened for repeated usage. The tubular teeth can be simply andinexpensively manufactured from hardened tool steel. The presentinvention thus provides for an improved hollow dome reamer providing forimproved economy of use and maintenance, and at lower manufacturingcosts than other conventional hollow dome reamers.

It should be recognized that other patterns of the teeth on the dome mayalso be suitable, such as a random scattering of locations of the teethon the dome, or a symmetrical balancing of locations of the teeth on thedome so that forces exerted on the dome would be generally balanced.Other suitable closure means also may alternatively be provided, such asby simply providing the circular base plate with peripheral threadsadapted to interfit with corresponding threads on the inner base portionof the dome, with the direction of the threading being such that thebase plate can be secured to the dome by rotating the base plate in thedirection of rotation of the dome.

FIGS. 25-32 portray still other, general aspects of the invention.Specifically, FIGS. 25-26 and 30-32 show one of such embodiments, i.e.,a rotary surgical reamer 420 comprises a hollow reamer body having adomed shape with an apex 424, a wall with an external surface 436 and aperipheral base 432, the wall defining a central cavity 434 and aplurality of spaced apart apertures 426 through the wall at a pluralityof spaced apart locations on the wall defining cutting sites. Thecutting sites define passageways 439 communicating between the externalsurface 436 of the wall and the central cavity 434 for passage ofremoved bone and tissue through the wall into the central cavity. Asingle mounting bar 440 extends diametrically across and is affixed to aback side of the peripheral base 432, the mounting bar having means inthe form of aperture 442 for centering a powered rotary driver thereto,in order to facilitate a bayonet-type connection between the reamer 420and driver in a manner described below. Mounting bar 440 may be moldedwith base 432, as shown by armatures 441 or the like which further aidin the connection mechanism.

Yet another general aspect of the invention is depicted in FIG. 27,where a pair of parallel mounting bars 440 a-b extend chordally acrossand are affixed to a back side of the peripheral base, the mounting barshaving means in the form of complementary notches 442 a, 442 b forcentering a powered rotary driver (not shown) for connection to thereamer 420 in a manner that will be appreciated by those in the art froma discussion of FIGS. 30-32.

Still another general aspect of the invention is shown in FIG. 28, wherean array of three radial mounting bars 440 a-c extend inwardly from andare affixed to a back side of the peripheral base 432, the mounting bars440 a-c respectively having central termini 442 a-c spaced from oneanother which functions as a means for centering a powered rotary driver(not shown) during connection to the reamer.

As shown in FIG. 29, the mounting bars 440 a-c may alternatively meetcentrally, as where a recessed driver connection is desired, asexplained below.

It will be appreciated that, although the various mounting barconfigurations described above in FIGS. 25-29 are depicted without theremovable cutting teeth 422 shown in FIGS. 30-32 below, it is preferredthat the apertures 426 which define the cutting sites have the removableteeth of the present invention.

The driver 444 represented in FIGS. 30-32 comprises a shank 446 with ashoulder 448, and a spindle head generally indicated at 450. Head 450further comprises a slide 452 mounted about a shaft 454, one end 456 ofwhich is fixed to the shank 446 and the other end of which is providedwith a flange 458 having a diameter greater than that of the shaft 454.The slide 452 is pushed on the shaft 454 axially in the direction ofarrow 460 by a spring (not shown) which applies it against the upperflange 462 of the shaft. The upper flange 458 serves as bayonet,preferably having a protrusion 464 at its center thus forming a collarshape. Formed in this collar are four L-shaped bayonet catches 466 whichare intended to receive the mounting bar 440 of the reamer. The slide452 is provided with four studs 468 which are parallel to the shaft 454and to which there correspond four holes 470 (FIG. 32) in the flange462, the studs passing through these holes in order to close the catches446 of the bayonet and thus lock the mounting bar 440 of the reamer inthe head 450 of the spindle shaft 454. In order to unlock the mountingbar 440, slide 452 is moved in a direction away from the flange 462(opposite the direction of arrow 460) so that mounting bar 440 is nolonger blocked in the catches 446 of the bayonet by the studs 470. Thisallows the driver 444 to be disassembled from the reamer 420. As shownin FIGS. 27-29, greater number and a different array of mounting barscan be provided as described above, in which case the number andlocation of the bayonet catches would need to be correspondinglystructured and arrayed so as to accommodate the particular choice ofdesign, respectively. Those skilled in the art will appreciate themanner in which the catches could be provided to adapt them to receivewhatever number and array is intended by the user, according to theteachings of the present invention.

Protrusion 464 could be stationary or spring-loaded, however, in usewith a reamer 420 of the type shown in either FIGS. 25-28 the protrusionfunctions as a centering means allowing for greater ease of effectingthe bayonet connection between driver 444 and reamer 420. In the casewhere protrusion 464 functions as a centering means, for example, inconjunction with the single mounting bar 440 having aperture 442 withinwhich it is received (FIGS. 30-32), the user experiences less effort andtime finding the correct orientation needed for making the bayonetconnection. This is important in minimizing the surgeon's time inperforming the bone preparation steps of the given implantationprocedure. The single mounting bar 440 (FIGS. 25-26 and 30-32) may becaptured by the bayonet connection in any opposed pair of the (four)catches 466 due to its relatively simple orientation requirements. Wherethe protrusion is spring-loaded (not shown), this allows use of the samedriver with the mounting bars 440 a-c of FIG. 29 which meet centrallyand require a recessed structure of the area between catches 466internally of upper flange 462, as will be appreciated by those skilledin the art. Alternatively, where centrally meeting mounting bars 440 a-care employed, as in FIG. 29, the protrusion 464 could be eliminatedaltogether.

The structure of those reamers 420 shown by FIGS. 25-29 yield furtherimprovements in the ease and speed by which removed bone matter can, inturn, be emptied from the cavity 434 within which it has been captured,for later reuse by the surgeon in the implantation procedure. This isbecause the underside of the base 432 of reamer 420 is more open andthus accessible to the surgeon's extrication.

The entire reamer 420, exclusive of removable and replaceable teeth 422,can be cast, molded or stamped. Where a molding operation is used, themounting bar 440 and armatures 441 (FIGS. 25-26) can be molded in thesame operation as the wall of reamer 420, thus reducing the number ofcomponents and steps needed to fabricate the reamer.

It will be apparent from the foregoing that while particular forms ofthe invention have been illustrated and described, various modificationscan be made without departing from the spirit and scope of theinvention. Accordingly, it is not intended that the invention belimited, except as by the appended claims.

1. A rotary surgical reamer assembly comprising: a hollow reamer bodyhaving a wall with an external surface and a base, the wall defining acentral cavity and a plurality of passageways through the wall definingcutting sites, the passageways communicating between the externalsurface of the wall and the central cavity for passage of removed boneand tissue through the wall into the central cavity; a shaft providedfor transmitting torque about a central axis of the shaft, for rotationof the reamer body; and a retaining member having a maximum dimension ata cross-section taken at its center which is substantially less than itslength dimension, the cross-section taken perpendicular to itslongitudinal dimension, and wherein its longitudinal axis extendsdiametrically across the base, traversing the central axis of the shaftand including a central aperture formed in a boss on the shaft, whereinthe aperture and shaft are aligned with one another along the centralaxis in a fixed relative position during rotation of the shaft andreamer body.
 2. The assembly of claim 1 wherein the shaft is adapted toarticulate with the aperture.
 3. The assembly of claim 1 wherein thebase further comprises a periphery, and the retaining member hasterminal ends that contact diametrically opposed portions of theperiphery, respectively.
 4. The assembly of claim 3 wherein the terminalends are affixed to a back side of the periphery.
 5. The assembly ofclaim 1 wherein the aperture is a rounded through-hole.
 6. The assemblyof claim 1 wherein the retaining member has a considerably flatconfiguration.
 7. The assembly of claim 1 wherein the aperture hasopposed openings each defining an edge with a flat surrounding surface,respectively.
 8. The assembly of claim 1 wherein the base furthercomprises a periphery and the retaining member is an integral barattached to the periphery.
 9. The assembly of claim 1 wherein theretaining member further comprising a leaf spring.
 10. The assembly ofclaim 1 further comprising closure means adapted to be secured to thebase for transmitting torque from the shaft to the reamer body, whilekeeping the bone and tissue contained in the central cavity.
 11. Theassembly of claim 2 wherein the shaft has a pin that articulates withthe aperture.
 12. A rotary surgical reamer assembly comprising: a hollowreamer body having a wall with an external surface and a base having aperiphery, the wall defining a central cavity and a plurality ofpassageways through the wall defining cutting sites, the passagewayscommunicating between the external surface of the wall and the centralcavity for passage of removed bone and tissue through the wall into thecentral cavity; a shaft provided for transmitting torque for rotation ofthe reamer body; and an elongated retaining member including a roundedcentral flat aperture formed in a boss of the retaining member, alongitudinal axis of the retaining member extending diametrically acrossthe base and affixed to opposed locations on the periphery for retainingthe shaft and the reamer body together.
 13. The assembly of claim 12further comprising closure means adapted to be secured to the base fortransmitting torque from the shaft to the reamer body, while keeping thebone and tissue contained in the central cavity.
 14. The assembly ofclaim 12 wherein the shaft has a pin that articulates with the aperture.15. A rotary surgical reamer assembly comprising: a hollow reamer bodyhaving a wall with an external surface and a base having a periphery,the wall defining a central cavity and a plurality of passagewaysthrough the wall defining cutting sites, the passageways communicatingbetween the external surface of the wall and the central cavity forpassage of removed bone and tissue through the wall into the centralcavity; a shaft provided for transmitting torque for rotation of thereamer body; and a considerably flat, narrow retaining member includinga rounded central aperture formed in a boss the retaining member havingterminal ends extending into the base, the retaining member extendingdiametrically across the base for retaining the shaft and the reamerbody in a fixed relative position along a central axis of the shaft. 16.The assembly of claim 15 further comprising closure means adapted to besecured to the base for transmitting torque from the shaft to the reamerbody, while keeping the bone and tissue contained in the central cavity.17. The assembly of claim 15 wherein the shaft has a pin thatarticulates with the aperture.
 18. An acetabular reamer assemblycomprising: a hollow reamer body having a wall with an external surface,a base and defining a cut axis, the wall defining a central cavity and aplurality of passageways through the wall defining cutting sites, thepassageways communicating between the external surface of the wall andthe central cavity for passage of removed bone and tissue through thewall into the central cavity; a holder with a shaft provided fortransmitting torque about a central axis of the shaft, for rotation ofthe reamer body; and at least two elongated retaining members extendingacross the base, spaced on either side of the cut axis, a centeringstructure comprising a boss cooperable between the shaft and retainingmembers, to align the central axis of the shaft with the cut axis in afixed relative position during rotation of the shaft and reamer body.19. The assembly of claim 18 wherein the retaining members extendcordally in parallel with one another across the base.
 20. The assemblyof claim 18 wherein the centering mechanism includes notches formed onthe retaining members.
 21. The assembly of claim 19 wherein theretaining members further comprise bars.
 22. The assembly of claim 18wherein the shaft and body are secured together by bayonet fastening.23. An acetabular reamer assembly comprising: a hollow reamer bodyhaving a wall with an external surface, a base and a cutter axis, thewall defining a central cavity and a plurality of passageways throughthe wall defining cutting sites, the passageways communicating betweenthe external surface of the wall and the central cavity for passage ofremoved bone and tissue through the wall into the central cavity; aholder with a shaft provided for transmitting torque about a centralaxis of the shaft for rotation of the reamer body, the holder includinga bayonet catch mechanism; and an elongated retaining member extendingdiametrically across the base and including a centering structurecomprising a boss, wherein the structure and shaft cooperate to alignthe shaft axis and the cutter axis in a fixed relative position duringrotation of the shaft and reamer body.
 24. An acetabular reamer assemblycomprising: a hollow reamer body having a wall with an external surface,a base and a cutter axis, the wall defining a central cavity and aplurality of passageways through the wall defining cutting sites, thepassageways communicating between the external surface of the wall andthe central cavity for passage of removed bone and tissue through thewall into the central cavity; a holder with a shaft provided fortransmitting torque about a central axis of the shaft for rotation ofthe reamer body, the holder including a bayonet catch mechanism; and aretaining member extending diametrically across the base and including acentering structure comprising a boss, wherein the structure and shaftcooperate to align the shaft axis and the cutter axis in a fixedrelative position during rotation of the shaft and reamer body.